Centrifugal casting machine



Dec. 11, 192s. 1,694,504

K J. A. GARDNER ET AL CENTRIFUGAL CASTING MACHINE Filed March 4, 1927 wwz/ inlays for dental work, jewelry, etc., diculty Patented Dec. 11, 1928o JOSEPH A. GARDNER AND DAVID S. GARDNER, 0F ME'MHIS, TENNESSEE.

CENTRIFUGAL CASTING MACHINE.

Application fled March It,

In the casting of very small articles of gold vor other similar and particularly highly refractory metals, such for instance as metal is experienced in ltransferring the metal from the crucible to the mold quickly enough and with sucient force to cause the metal to flow into the delicate parts. These difficulties have been partially solved by what are known as centrifugal casting machines, in which the mold is placed on a rotatable arm and a cruci ble located on the samearm, between the mold and the center of rotation, and in which after the metal'in the Crucible has been suihciently heated, the arm is caused to rotate rapidly and the metal to thereby be thrown into the mold-centrifugally. In these machines howA ever, many incidental points are `as\ yet unsolved or only crudely solved and itis'to these points that our invention is lar'gely directed. Among these points are, rst, that while the finer parts of the castin are taken care of by the centrifugal action, t e amount oflrotati'on securable by the spring action ordinarily used,"is insuilicient to provide a duration of rotation which will permit the larger parts of the casting to solidify before it ceases, and therefore releases have been interposed which permit the arm to rotate after the spring acf tion is spent. i l

Second, the Crucible and mold is ordinarily heated and the metal melted before these parts arel placed on the arm, and means for eecting quick and positive attachment of the crucible and mold must be rovided; and

Third, the motion im arte to the arm being sudden and power ul, provision should be made for positioning the Crucible and mold so that the initial tangential motion may be utilized,butthese partsbeing the heavier parts and at the end of the arm, provision should be made for accomplishing rigidity after they have taken upy a radial position in order to eectually utilize their inertia and keep the arm in balance. i

The objects of this invention are, and this invention relates,

(l) To means for reducing the frictional relation between the parts initiating motion and those continuing the rotation after the power of the motor has been spent; such ob- 19.27. Serial No. 172,87d.'

ject 1primarily being accomplished by placing the ocking and releasing means at the point of ultimate attachment of the arm to the source of power;

(2 To means `fory effecting the secure attachment of the Crucible and mold parts to the arm;

(3) To means for limiting the movement of themold carrying arm initially to a tangential position, and thereafter to a radial position; and

(4) To means for improving generally, the construction of such a machine.

The means by which the foregoing and other objects are accomplished, and the man# ner of their accomplishment, will' readily be understood from the following specification, on reference to the accompanying drawings, in which,-

Fig-1 is a sectional side elevation of the machine with crucible and mold in place.

Fig. 2 is a lan view, with the crucible and mold removed, and

F ig. 3 is a fragmentary sectional side ele- Vation on the line III-HI of Fig. 1, showing the'f'neleasing pawl.

Referring now to the drawings in which the various parts have been indicated by numerals,-1O is a casing in which is mounted a vertical shaft 11, supported at its lower end on a ball .12, and provided near its upper end with a ball bearing assembly 13, the inner portion of which is secured on the shaft and the puter portionin the upper portion of the casing- 14 is a retaining cap securing the bearing in the casing. 5 15 is a flat coil spring, one fend of which is secured in any desired manner to the shaft and the other to the casing.

16 is a collar, secured above' the bearing 13, to the portion 17 of the shaft, byia pin 18, passing through the shaftand coilar and projecting laterally therebeyond. Above the section 17 the shaft is reduced in diameter to form a shoulder against which the inner portion of a ball-bearing assembly 19 is forced and secured to the shaft by a nut 20.

21 is the throwing arm, to which is secured, in any desired manner, a retaining member 22 into which the outer half of the ball-bearing assembly 19 has been forced. 23 is allele quick and` i in the through which the nut 20 projects.

Projecting laterally from the member 22 is a pin 24 on which a pawl 25 is hinged and depends into the path .of the pin 18. This pawl--as will be seen b reference to Fig. 3 swings upward to permit its passage over the pin in one direction, when the pawl moves to the ri ht in that View, but is restrained by the shoul er 26 from swinging lin the opposite direction,so that it will engage the pin when the pawl is moved to the left in winding, or be en aged by the pin when the latter is fmove to the right by the spring action.

Secured to one end of the throwing arm 21 is a bearing 27, through which asses a 1n 28 rigidly securedv in one end o an oscil atable extension 29 of the throwing arm, thus f providing fortthe extension of a pivotal support, but one substantially rigid against vertical movement. 30 is a brace secured to the extension and bracing affainst the lower Aend of the pin 28 to give additional rigidity to that member. 31, 32 are lugs or stops on the arm 21, and 33 is a pin secured in, and depending below, the extension 29 which pin engages the lug 31 to determine a position of the arm tangential to the circle of movement of the pin 28, and which pin likewise engages the lug 32'to`determine a. true radial position of the extension.

The end 34 of the extension arm 29, is preferably turned upwardly at right angles to the arm to form a stop Aor abutment. A shield 35 may be secured thereto and form a 'part ofthe stop. 36 is a slot in the arm having an enlarged eye 37 located at the inner end o the slot. Preferably this slot is slightly wider at its inner end than its outer end. 38 is the crucible and 39 the mold, preferably made integral and provided with a pin 40, projectin downward therefrom, the pin having an en ar ed head 41, which issmaller than the `eye 3 -butlarger than the slot 36. This provides ameans for uickly and solidly attaching the crucible an mold to the arm, b slipping the head 41 of the pin through t e e e 37 and then moving the crucible and mo d radially outward until 'the end-of the mold abuts solidly against the stop 35. The tapered slot allows at the same time a minor wedging action of the pin 40 against the slot sides, but .such wedgin should not be sufficient to prevent the mo d from seating firmly against the stop. Where longer crucible-mold -assemblies are used, a larger pin may be used in order to get a similar wedging action ata point more remote from the stop. It will be seen that not only is the mold guickly and firmly engaged, but centrifugal orce 0f the machine when in use additionally tends to .make the attachment more secure. 42 is a weight adjustably secured to the opposite end of the throwing arm, which weight may bemoved inward or outward until it balances the weights on the opposite arm-end secured by tightening the 44 is a pin, vertically slidable in the casi ing 10, which may be raised upward into the path of the arm 21 to form a stop therefor, should same be desired. The casing 10 may be secured :to any suitable support in any desire/d manner.

In use the wei ht 42 is adjusted to the proper location to alance the particular crucible and mold to be used and these, after the metal has first been melted in suitable apparatus, are engaged with the slotted arm 29, with the mold firmly seatedagainst the stop. The arm 21 is then turned in the direction of the arrow A in Fig 2, until the spring 15 is wound up. During such winding the pin 33 moves the extension arm in the same direction of rotation and prevents its swinging in the wrong direction. After winding, the arm 21 is released and the spring allowed to rotate it rapidly in the reverse direction. At the start of such reverse motion, the mold tends by inertia to lag behind and the extension arm assumes a tangential instead of radial posi- I tion. At such time the pin 33 engaging the lug 31 prevents the arm from swinging too far inward. After the parts have been set in full motion the extension arm ain assumes a radial position, the metal in t e crucible thus being,` at all part-s of the movement, impelled toward the mold.

When the springhas spent its force, the arm continues to revolve, the ball-bearing 19 substantially eliminating friction and the pawl 25, Fig. 3, riding over the pin 18 with a minimum of resistance, so that with the.

arm mounted for rotation at the ultimate point of connection with the shaft, frictionis practically eliminated and rotation will continue for a very considerable period, thus allowing the metal in the mold to cool and solidify whiley still under centrifugal pressure. During this period too, the pm 33 engaging the lug 32 prevents the mold end of the arm from over-running there'mainder ment, maintains them in balance.

It will of course be understood that the drawings are illustrative only, and that various modifications may be made in the de'- tails of construction without departing from the spirit of our invention. We therefore, wish it distinctly understood that we do not wishto limit ourselves to the 'details herein shown and described, except as same may be specifically hereinafter set out in the claims.

Having thus disclosed our invention, what we claim is 1. A casting apparatus comprising a vertical shaft, means for driving said shaft during a limitedperiod, a mold carrying arm mounted for free rotation on' the extreme upper end of said shaft, a pin projecting from said shaft, a pawl carried by said arm, de-

lthereof and in maintaining them in alignpending into the path of said pin during tatavble arm, and a. in projecting from said action of said driving means, and over riding extension arm an disposed between said 10 said pin when driving action is spent. lugs f 2. A casting apparatus, comprisin a rotattestimony whereof we have hereunto set 6 able arm, an extension arm pivo thereto our names.

and means for limiting'. the swing of said extension arm, comprising oppositely disposed JOSEPH A. GARDNER. ugs projecting longitudinally from said ro- DAVID S. GARDNER. 

